Fragile X Syndrome Mutations Found With Comprehensive Testing Method

In Clinical Chemistry, a team from the Hunan Jiahui Genetics Hospital, Central South University, and elsewhere present a long-read sequencing strategy for uncovering clinically informative expansions in the X chromosome gene FMR1 that cause fragile X syndrome (FXS), an inherited intellectual disability condition. The researchers used Coriell Cell Repository samples, along with available clinical samples from 62 individuals representing 21 FXS-affected families to develop and assess their "comprehensive analysis of FXS" (CAFXS) assay. When they compared CAFXS to Southern blot or triplex repeat-primed PCR, the authors found that the sequencing strategy uncovered known gene expansions, along with rare genetic variants. "Accurate and complete genetic characterization of repeat expansion disorders has been challenging using conventional methods," they write, calling CAFXS "a comprehensive assay for identifying FMR1 CGG expansions, AGG interruptions, rare intragenic variants, and large gene deletions, which greatly improves the genetic screening and diagnosis of FXS.